Reachout Orthopedics - Issue 2

first MTPJ OA severity [30]. Findings from a smaller elderly population have shown that older people with radiographicOAof the talo- navicular joint and navicular-first cuneiform joint exhibit flatter feet represented by the Arch Index [31]. A diagnostic rule developed for first MTPJ OA suggests five clinical observations canaccurately identify thepresence or absence of radiographic first MTPJ OA in patients with first MTPJ pain [32]. These include pain duration longer than 25 months, the presence of a dorsal exostosis, hard-end feel, crepitus and less than 64 ° of first MTPJ dorsiflexion. More recently, a consensus study provided five recommended assessment components for first MTPJ OA, including pain on walking over the past week, first MTPJ and ankle joint range of motion, foot posture (foot posture index), resting calcaneal stance position and palpation to determine pain location [33]. Findings suggest that some of these physical examinations may be of limited use for discriminating the presence or absence of symptomatic midfoot OA, but a number may hold some value in diagnosing first MTPJ OA. Further work would be beneficial to determine if these and other clinical measures may be useful in discriminating between the presence and absence of symptomatic OA in all identifiable foot joints. Imaging Assessment The latest recommendation from the European League Against Rheumatism is that imaging is not required to make a diagnosis of OA in pa- tients with a typical presentation of the disease [34]. Routine follow-up imaging to monitor disease progression or treatment response is also not recommended. The exceptions to these include cases where the patient’s pres- entation is atypical and thus imaging may be needed to confirm a diagnosis of OA or make a differentiation diagnosis, or if there is a rapid and unexpected progression of symptoms, and imaging may be used to see if progres- sion is related to symptoms or an additional diagnosis. In such cases, the guidelines rec- ommend plain-film radiography in the first instance prior to other modalities. The vast majority of the recommendations were made based on studies from other sites given there is very little research available regarding imaging for foot and ankle OA. One exception was a small study that found that when ultrasound imaging was added to clinical assessment findings, the diagnostic confidence of rheuma- tologists in differentiating OA from inflamma- tory arthritis of the hands or feet was signifi- cantly increased [35]. Notwithstanding these recommenda- tions, radiography is routinely used in the primary care setting [36], and in clinical re- search, to confirm diagnosis and/or OA se- verity grade. Regarding grading, a systematic review [37] of the radiographic prevalence of foot OA from 27 studies found that most (70%) used the Kellgren and Lawrence (KL) system [38]. This system classifies OA based on the presence or absence of osteophytes and joint space narrowing, using a scale of 1 (doubtful OA) to 4 (severe OA). The majority of studies (95%) in the review classified OA as being at least grade 2 (mild OA) [37]. Whilst the use of the KL system allows comparison between studies of radiographic OA at more proximal joints such as the knee, it has been argued that it places too much dependence on the presence of osteophytes, which are implied to precede joint space narrowing in a chronological progression of OA [39, 40]. Furthermore, another review reported large variation in the definition and grading of OA using the KL system [41]. In response to these limitations, Menz and colleagues [42] developed a foot-specific atlas which classifies radiographic OA of the first MTPJ, first cuneiform-metatarsal joint, second cuneiform-metatarsal joint, talo-navicular joint and naviculo-cunieform joint [42]. The atlas overcomes the major disadvantages highlighted in previous radiographic foot OA studies by (1) obtaining dorsoplantar and lateral views; (2) requiring x-rays to be taken while weight-bearing; and (3) grading both osteophytes and joint space narrowing separately on a scale of 0 (absent) to 3 (severe osteophyte or joint fusion). As an example, Fig. 1 is a dorsal view of the first MTPJ showing the grades for joint space narrowing. Radiographic OA is defined as present at any of the five foot joints if there is a score of 2 or greater for either osteophytes (indicating a moderate or severe osteophyte) or joint space narrowing (indicating severe joint space narrowing or joint fusion at at least one point) on either the dorsoplantar or lateral view [42]. The authors reported that the atlas had moderate to excellent within-rater reliability, and mostly fair to excellent between-rater reliability. The overall foot OA score was also found to possess moderate to excellent within- and between-rater reliability [42]. An additional atlas has recently been developed to grade radiographic OA at the ankle (tibiofibular and tibiotalar) and subtalar (talocalcaneal) joints [43]. The ankle and hindfoot atlas grades osteophytes and joint space narrowing from 0 (normal) to 3 (severe) from weight-bearing mortise and lateral views. Osteophytes are graded in the medial and lateral compartments from the Fig. 1: Dorsal projection of the first metatarsophalangeal joint showing the grades for joint space narrowing based on the atlas developed by Menz et al . [42]. A grade of 0 indicates no joint space narrowing, 1 indicates definite joint space narrowing, 2 indicates severe joint space narrowing and 3 indicates joint fusion at at least one point. Reprinted from Menz et al . [42] with permission from Elsevier. The latest recommendation from the European League Against Rheumatism is that imaging is not required to make a diagnosis of OA in patients with a typical presentation of the disease. 20 reachOut Orthopedics